Production of asphalt



y 1941- D. B. HARRISON 2,247,371

PRODUCTION OF ASPHALT Filed June 7, 1958 Inventor Donald 3. Harrison y/M QM Aiiorney Patented July 1, 1941 PRODUCTION OF ASPHALT Donald B. Harrison, Philadelphia, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa, a corporation of Pennsylvania Application June '7, 1938, Serial No. 212,300

8 Claims.

The present invention relates to the treatment of bituminous materials, and particularly bituminous materials such as cracked or uncracked petroleum residuum.

A principal object of this invention is the produotion of improved asphalts from bituminous residues, and particularly from petroleum residuum containing about 10% or less by weight of asphaltenes, which will not yield homogeneous asphalts when treated according to conventional methods.

A further object of this invention is the production of homogeneous asphalts having a negative Oliensis test from domestic crude petroleum residuum having a relatively low content of asphaltenes. Such test is described in A. S. T. M. Proceedings, part II, vol. 39, (1936) page 506 et seq., and is being widely adopted in asphalt specifications as an index of homogeneity of asphalt products.

A further object of this invention is the treatment of residuums produced by the cracking or non-cracking distillation of petroleum; residues from the hydrogenation of petroleum; heavy residual oils produced by polymerization; and residues produced by the treatment of petroleum oils with selective solvents or with asphalt-precipitating agents such as petroleum naphtha, pentane, butane, propane, ethane and the like.

In the production of asphalts, it has heretofore been customary to subject asphaltic crude oils to fire and steam distillation whereby volatile oils are removed, leaving an asphaltic residuum, or to subject the asphaltic residuum so produced to oxidation with air at elevated temperatures to yield asphalts of increased softening point. However, it has been found impossible to produce from petroleum residuums containing less than about 10% by weight of asphaltenes, satisfactory asphalts exhibiting a negative Oliensis test, by air oxidation, distillation or blending, or combination of such steps.

I have found that by treating bituminous materials, and particularly petroleum residuum, with a gaseous mixture comprising sulfur dioxide and air or oxygen-containing gas at elevated temperatures such that reaction of the sulfur dioxide and air with the petroleum residuum is effected, I am able to obtain asphaltic materials of markedly increased melting point.

Furthermore, in accordance with my invention I am able to produce homogeneous asphalts, as indicated by a negative Oliensis test, from petroleum residuums which will not produce such asphalts when processed in the conventional manner. In other words, petroleum residuums which cannot be converted into homogeneous asphalts by conventional distillation, air blowing, and blending or combination of such steps are amenable to my treatment and Will yield homogeneous asphalts of the character of those derived from asphaltic crude oils such as Mexican and Venezuelan.

In carrying out my invention, a bituminous material such as a crude petroleum residuum is subjected to the action of sulfur dioxide, in the presence of an oxygen-containing gas such as air, at elevated temperatures of the order of from about 300 F. to about 550 F. for a period of time varying from about hour to about 8 to 10 hours or more, depending upon the rate of reaction between the sulfur dioxide-air mixture and the petroleum residuum. The quantity of sulfur dioxide employed may vary from a few percent by weight up to 20% or 25%, and is preferably of the order of from about 2% to about 6% by weight of the residuum treated. In general, upwards of of the quantity of sulfur dioxide brought into contact with the petroleum residuum is caused to react therewith, provided the contacting is carried on in an efficient manner.

Treatment of the residuum may be effected at substantially atmospheric pressure by simply blowing sulfur dioxide and an oxygen-containing gas, such as air, through a mass of the bitumen at elevated temperatures, or the sulfur dioxide and air may be admixed with the residuum at elevated temperatures and under a substantial superatmospheric pressure of the order of 30-100 lbs/sq. in. or higher. In one modification of my process, sulfur dioxide and air may be passed through a pool or series of pools of petroleum residuum maintained at a temperature of the order of from about 300 F. to about 550 F., or the sulfur dioxide and air may be diluted with nitrogen, carbon dioxide or flue gas and brought into contact with the heated residuum. 0r, alternatively, heated residuum may be sprayed or flowed downwardly through a tower in intimate countercurrent contact with gaseous sulfur dioxide and an oxidizing gas such as air. Unreacted sulfur dioxide and air from the contacting step may be recirculated to said contacting step, if desired.

In accordance with my invention, I may treat the so-called non-asphaltic petroleum residues containing relatively small amounts of asphaltenes, i. e., less than about 10% by Weight of asphaltenes, such as are derived from Texas and Oklahoma or other non-asphaltic crudes, with sulfur dioxide and an oxygen-containing gas at elevated temperatures to produce asphaltic materials of improved characteristics. Such. materials, when subjected to further treatment involving distillation and blending with oils or residues of difierent nature, will produce homogeneous asphalts of the general character of those derived from the true asphaltic crude oils of Mexico and Venezuela. Petroleum residual oils, such as those resulting from the distillation of Texas, Oklahoma or other non-asphalt base crudes, cannot be converted into asphalts having a negative Oliensis test and the characteristics of Mexican or Venezuelan asphalts by merely blowing with air at elevated temperatures and distilling and blending the air-blown products with other oils or residues.

The principal advantage of my process is the ability to produce, from domestic crude petroleum or petroleum deficient in asphaltenes, specification asphalts which are more homogeneous, as measured by the Oliensis test, than asphalts produced from the same residuum by conventional methods of air oxidation, distillation and/r blending. A negative Oliensis test indicates a homogeneous asphalt, while a positive test indicates a non-homogeneous asphalt.

My invention may be further illustrated with reference to the accompanying drawing, which shows diagrammatically a system suitable for carrying out my process.

Petroleum residuum, containing less than substantially by Weight of asphaltenes, is supplied from storage (not shown) by means of valve-controlled pipe I to pump 2, and is delivered thereby to a suitable heating device, such as heating coil 3, wherein the temperature of the residuum is raised, for example, to about 500 F. The heated residuum is then introduced into the upper end of a reaction chamber 4 by means of pipe 5, and is passed countercurrently downward through the chamber in inti mate contact with upwardly flowing streams of a reactive gaseous mixture comprising air and from about 2% to 6% by weight. based on the residuum, of S02. The air and S02, in the proper proportions, are supplied to the lower section of the reaction chamber 4 by means of valve-controlled pipes and 1, respectively, pump 8, and a spray head Sprovided with suitable nozzles. The rate of flow of the heater residuum and the gaseous mixture through the reaction chamber is adjusted so that sufiicient time is provided for the reaction between the residuum and the air-S02 mixture to be substantially completed. Unconsumed air, S02, and gaseous reaction products including HzS are withdrawn from the upper end of the reaction chamber 4 by means of pipe is and may be vented through valve-controlled pipe I l or a portion of such gaseous products may be recycled to the chamber by means of valve-controlled pipe I2, preferably in admixture with air and S02 supplied through valvecontrolled pipes 0 and 1, respectively. The heated residuum, the asphaltene content of which has been substantially increased by the air-S02 treatment, for example, to 25% to 30% by weight, is Withdrawn from the bottom of chamber A! and passed by means of valve-controlled pipe 3 to pump 14, and is pumped through valve-controlled pipe IE to mixing vessel [6 provided with agitating paddles I I mounted on a rotatable shaft i8. At this stage, there may be admixed with the treated residuum, a quantity of high boiling hydrocarbon oil or residuum rich in resins, for example, oil containing from about 30% to about 45% or more by weight of resins. Such oil may be supplied from storage (not shown) by means of valve-controlled pipe E9 to pump 20, and pumped through heating coil 2!, pipe 22, and valve-controlled pipe 23 into the lower section of the mixing vessel It. In. the mixing vessel It, the treated residuum and the oil rich in resins are thoroughly admixed, and the heated mixture is then introduced into the stripping column 24 provided with bubble trays or perforated baffles 25 and steam injection nozzle 26. In the stripping column 2d, the volatile oils produced in the initial treatment of the residuum with air and S02 are vaporized and Withdrawn from the top of the column through valve-controlled pipe 21, and may be disposed of as desired. The resulting asphalt, stripped of volatile oils, may be withdrawn from the bottom, of column 24 by means of valve-controlled pipe 28, and passed to storage (not shown).

As an alternative procedure, the treated residuum from chamber A! may be passed by valvecontrolled pipe 5%, pump id and valve-controlled pipe 29 into the stripping column 26, stripped therein, by means of open steam, of its content of volatile oils, and the stripped residuum then withdrawn from the bottom of column 25 and passed by means of valve-controlled pipe 36, and pump 3!, to the mixing vessel 32 provided with agitating paddles 33 mounted on a rotatable shaft 34. In the mixing vessel, the stripped residuum may be admixed with a suitable quantity of high boiling oil rich in resins supplied through valve-controlled pipe i9, pump 20, heater 2i, and valve-controlled pipe 35. The resulting asphalt may be withdrawn from the mixing vessel 32 by means of valve-controlled pipe 36, and passed to storage (not shown).

My invention may be illustrated by the following examples, which are not to be construed as limiting the scope thereof. In the following table the results obtained by treating a petroleum residuum, at elevated temperatures, with air alone are compared with the results obtained by treating with air. in the presence of sulfur dioxide. A crude petroleum residuum (17% bottoms from West Texas crude oil) having a Saybolt Universal viscosity of 839 seconds at 210 F., an A. P. I. gravity of 12.5", a flash point of 560 F., a fire pointof 640 F., and comprising 52.5% oil, 44.0% resins, and 3.5% asphaltenes was blown with air at a temperature of about 500 F. for a period of 1 hours. Three other portions of the same residuum were blown with air under the same conditions except that varying amounts of sulfur dioxide were present in the The treatment was carried on in each case to produce a product having a softening point of the order of F.- F., from which volatile oil constituents were removed by vacuum distillationto produce, in each case, a residue having a softening point of the order of about F. Each residue was then blended with about 25% of the initial, untreatedpetroleurn residuum rich in resins to produce asphalt hav ing a softening point of about 120 F.

Weight percent SO; em-

ployed (based on residuum 2. 2 4. 4 5. 4 Cu. ft. air/hour/ga]. re-

siduum 18. 2 l8. 5 l8. 3 l0. 6 Temperature of treatment .F 500 500 500 500 Length of treatment hours 1% 1% 1% ll Softening point of treated residuum F l 112 110 112 110 Residue from vacuum distillation of treated residcum Softening point -.F-. 137 r32 r33 135 Oliensis test Positive N egative Negative N egalive Blended asphalt Weight percent residue from vac. dist 74 70 72 76 Weight percent untreated residuum 26 24 28 24 Properties of blended asphalt Softening point. F 121 121 120 123 Oliensis test Positive Negative Negative Negative It will be seen from the results above tabulated that treatment of petroleum residuum at elevated temperature with air and sulfur dioxide, followed by removal of volatile oil components by distillation, produces asphaltic material having a negative Oliensis test, whereas the residuum similarly treated with air alone has a positive Oliensis test, thus indicating non-homogeneity. Furthermore, the residuum treated with air and sulfur dioxide, when blended with untreated residuum, has a negative Oliensis test, whereas the residuum treated with air alone and then blended, has a positive Oliensis test. While, in th}e above examples, an untreated petroleum residuum rich in resins is employed as a blending material, other high boiling oils rich in resins may be utilized, for example, extract oil fractions resulting from the selective solvent treatment of residuums or other high boiling hydrocarbon oils. Oils containing from about 30% to 45% by weight, or more of resins, are considered to be rich in resins and are suitable for use in accordance with this invention.

In producing specification asphalts having the characteristics of steam refined Mexican or Venezuelan asphalts, I may treat petroleum residuum deficient in asphaltenes with sulfur dioxide and air at elevated temperature, and thereafter either remove volatile oils from the treated residuum by distillation and then blend the distillation residue with oils rich in resins, or I may blend the treated residuum with oils rich in resins and then remove from the blended material volatile oils by distillation. Alternatively, I may simply blend the treated residuum with resins or oils rich in resins, removal of volatile oils by distillation being dispensed with. The asphalts produced in accordance with my invention may be subjected to further treatment, such as air oxidation, when it is desired to produce high softening point products.

What I claim is:

1. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and freeoxygen containing gas at an elevated temperature such that reaction of the sulfur dioxide and free-oxygen containing gas with the residual oil is effected, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

2. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and freeoxygen containing gas at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur dioxide and free-oxygen containing gas with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

3. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with free-oxygen containing gas and from about 2% to about 6% by weight of sulfur dioxide at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur dioxide and free-oxygen containing gas with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

.4. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and air at an elevated temperature such that reaction of the sulfur dioxide and air with the residual oil is effected, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

5. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and air at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur dioxide and air with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

6. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with air and from about 2% to about 6% by weight of sulfur dioxide at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur dioxide and air with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

'7. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and air at an elevated temperature such that reaction of the sulfur dioxide and air with the residual oil is effected, and blending the treated residual oil with high boiling oil rich in resins.

8. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur dioxide and air at an elevated temperature such that reaction of the sulfur dioxide and air with the residual oil is efiected, blending the treated residual oil with high boiling oi1 rich in resins, and removing from the blended material volatile oils by distillation.

DONALD B. HARRISON. 

